Propeller



lll

f which a plurality of Patented Sept. 6, 1932` UNITED STATES PROPELLER applicati@ med may 2o,

This invention relates to propellers, and moreV particularly to propellers of the hollow metal type.

Heretofore, there have been proposed hollow metal propeller blades which possess several advantages over' wooden propeller blades, among which may be mentioned durability, rigidity,' and increased strength, such factors rendering this type of propeller blade especially adaptable for use on aircraft. In all prior constructions of hollow metal propeller blades, how-ever, extreme difculty has been experienced in forming the inner end o'r root of the blade in such a manner as to adapt the same for reception by the usual hub, and at the same time to impart sucient strength and rigidity to the blade root to successfully withstand the enormous forces to which the same is subjected during operation of a propeller embodying this type of blade.

It is accordingly' one of the objects of the present invention to provide a hollow metal propeller lso constructed as to obviate the above difficulties.

Another object of the invention is to provide a novel propeller blade construction of the built-up type having a separately formed root or hub portion. Still another object is to provide in a holl'ow propeller blade constructiom a novel, separate, integrally-formed root member adapted to be secured to a lurality of blade members whereby an exceedingly strong and durable propeller blade is effected.

A further object is to provide a novel blade root or hub member for a propeller blade, having a plurality of integrally-formed outwardly extending arms adapted to constitute a portion ofthe edgesfof the blade and to blade members are adapted to be secured, ingly strong and eflicient propeller blade `may be produced at minimum cost.

Other objects and novel features of the i11- vention will appear more fully hereinafter from the following detailed description when taken in connection with the accompanying drawing. It is to b e expressly signed as a denition whereby an exceed-y 1931. Serial No. 538,801.

understood, however, that the drawing is for purposes o f illustration only and is not deof the limitsy of the invention, reference being had for this purpose to the appended claims.

Referring to the drawing, wherein like reference characters refer to like parts throughout the several views:

Fig. 1 is a plan View of a blade root member embodying the present invention;

Figs. 2, 3, 4, 5, 6, and 7 are axially spaced transverse sections of the root member shown in Fig. l;

Fig. 8 is a plan view of a finished blade embodying the root member shown in Fig. 1, a portion oflsaid member being illustrated in section; and

Figs. 9, 10, 11, 12, sections of the finished blade.

Referring more particularly to Figs. 1-7, a blade root member constructed in accordance with the present invention is illustrated therein as constituted by a substantially cylindrical inner end or hub portion 14 which has preferably formed integrally therewith an annular iange or shoulder 15 adapted to fit within the socket of the usual propeller hub. Adjacent the other end of the hub portion 14, the blade-root member is formed with a pairof outwardly extending divergent arms 16 and 17 for a purpose which will a pear more fully hereinafter. Preferably, tlp blade root member is formed in one piece, as by forging, and in order to weight construction, the member is hollow, as indicated on the drawing.

As will be observed from Figs. 3-7, 'each of the arms 16 and -17 is gradually tapered from one end to the other and is provided on either side thereof with ledges 18 and 19 which are adapted to receive the inner ends 0f a pair of blade members 20 and 21, these last named members being secured in said ledges by any suitable means, as for example, by welding.

Prefera-bl each of the blade members 20 and 21 is reinforced by 4laminations-22 and 23 respectively, and these laminations may be secured to the blade members under tension, if desired, in order torelieve the outer faces provide a light and 13 are transverse ofthe inished'blade' of a portion of the tension loadI imposed thereon by reason' of the centrifugal force developed during operation of a propeller embodying blades constructed 5 in this manner.

therein. It will be observed from'Figs. 9 and lcient. depth to cause the outer surfaces of the blade members to t flushwith the outer surfacesv of the arms 16 and 17 in order to produce a the blade maythereafter be placed within a suitable die after proper heating, and a fluid under pressure may be inserted within the blade in order to expand the same and force the exterior surface thereof into intimate contact with the surfaces of the die, to effect the blade shape desired. The blade vthus formed may be thereafter burnished and polished in a manner well known to those skilled inthe art. V A

There is thus provided by the present invention a novel propeller blade constructed of the built-up hollow metal type embodymg a separately formed root mem er. Byforming the inner end portion or` root of the blade as a separate member, an unusually strong and durable structure is secured. The provision of the outwardly extending arms on the root portion serves not only to effect a firm and secure anchorage for the inner end portions of the 'blade members, but also forms a portion of the leading and trailing edges of c he finished blade, and thus reinforces these portions which are subject to tremendous bending and twisting forces during operation. Such construction also eliminates all marginal welds or seamsI adjacent the inner end of the propeller blade which might have a tendency to open during operation.

Though only one embodiment of the invention has been illustrated anddescribed, it is to beexpressly understood that the same is not limited thereto but various forms.` For example- -lmore'than two blade-supporting arms may providedv for the root member land more han one lamination ma be employed with each blade member, if esired. It is also to be understood that the inner ends of the blade members may be secured in the ledges ofthe hub member by means other than welding, as for example, by means of rivets. Other lchanges maybe made'in the relative sizes, shapes an locations of the component parts of the ine ventlon, as will now be understood by those u skilled in the art, without departing from the -spect to said hub portion, and the inner spaced.

that the aforementioned ledges are of'sufiiv p i prismg, a separately smooth blade contour. If desired,

edges of the blade,

may'mbe embodied in spirit thereof. lReference will, therefore, be

had to the following claims for a definition of the limits of the lnvention.

What is claimed'is:

1. A built-up metal propeller blade having a separately formed root member, said member having ,a substantially` cylindrical hub portion, a pair of oppositely disposed divergent arms integrally formed with rea ledgedisposed on either side of said arms, and a pair of laminated. blade members secured together at their ou'ter extremities and secured at their inner extremities 2. A hollow metal in said ledges.

ropeller blade comormed root member, said member having a cylindrical hub portion and a pair of outwardly extending arms, a pair ofbl'ade members marginally secured together at their outer end ortions, and means for securing said bla e member to said arms at the inner end portions of'said members.

3. A metal propeller blade comprising a hollow root member having a pair of longitudinally extending arms adapted to constitute a portion of the leading and trailing and blade members secured to' adjacent portions ofeach of said arms and to each other to form a hollow metal blade.

4. A metall prop ller blade comprising va hollow root member having a pair of oppositely disposed divergent arms, each ofv said arms being providedl with ledges, and blade members secured in saidv ledges and` to each other to form a hollow propeller blade.

' 5. In a metal propelerblade, a separately formed root member havin a substantially cylindrical end portion, an wardly extending arms integral therewith, each of said arms being provided with 'a ledge on either side and disposed inwardly of the marginal portion thereof. v

v6. In a metal -propellJer blade, a separately formed root member havingv a substantially cylindrical hub portion, a pair of longitud inally extending arms integrally formed with said hub `portion and gradually taper'- inv outwardly, each of saidarms being provi ed with ledges on either side thereof and adaptedto receive the inner of blade members.

'7. Abad@ webmaster for a bladeY comprising a substantially c rical v end portion, a pair of longitudina y extending the leadin and trailing edges of the blade said arms eing forme inte rally with sai cylindrical-end portion an means formed on each of said arms for receiving a 'pair d of blade members.

8. A propeller blade comprising a hollow, forged root memberl having a substantially cylindrical end portion, a plurality of outa pair of outends of a pair ller arms vadapted to constitute a portion ofV portion wardly tapering arms integrally formed therewith, a plurality of blade members, a ledge provided on either side of said arms or receiving the' inner ends of said blade members, said members being marginally secured together adjacent the outer ends thereof to form with said root member, a hollow propeller blade.

A propellerl blade comprising a separately formed root member having a substantially cylindrical end ortion, a plurality of outwardly exten 'ng supporting members formed integrally with said hub said members forming a portion of the lea ing and trailing edges of the blade, and a plurality of blade members secured to each other and to said supporting members. 10. A propeller blade` comprising a separately formed hollow root member having a substantially cylindrical end portion, a pair of outward] extending divergent arms formed integral y with sald end portion, said arms forming a portion of the leading and trailing edges of the blade, a ledge formed on either side of each of said arms and disposed inwardly of the marginal orthereof, and a pair of blade mem rs secured together adjacent their outer end portions and welded in said ledges adjacent their inner end portions to form with said root member a hollow propeller blade.

11. A. propeller blade comprising a separately formed root member having a pair of outwardly extending arms adapted to form portions of the leading and trailing edges of the blade respectively, said arms being ada ted to be secured to a pair of blade mem ers for com leting the blade.

In testimony whereof I have signed this specification.

CLIN TON H. HAVILL.- 

